The aims of the Data Analytic Core are to collaborate with project directors from each project with respect to protocol development (including research design, sampling, measurement, and analysis); perform standardized methods of data entry, manual and computer-driven edit checking, and database management; establish and maintain a core database across all studies in the program project; provide a secure repository for individual data sets (updated on a weekly basis) generated by each of the projects and maintained within the Data Analytic Core database; collaborate with project directors in the conduct of their studies and perform the required data analytic tasks; as a collaborator, review and participate in the writing of abstracts and manuscripts using data collected and assume full co-authorship responsibilities; and apply state-of-the-art analytic techniques and, if needed, develop new statistical methodology. A proactive approach will be taken to foster effective biostatistical collaboration in the early planning of all projects. Contact will be achieved through project-specific monthly meetings conducted by the project PI and all three Ph.D. biostatisticians, as well as through Executive Committee membership of the core director. Also, meetings will be held more frequently between the project PI and the project-specific biostatistician on as-needed basis if, for example, abstracts are due for a meeting or a manuscript is under review prior to its submission. If interesting methodological issues arise during statistical analysis, a special meeting of biostatisticians from the core and faculty from the Division of Biostatistics will be held. Finally, the core will facilitate the overall objective of this program project by analyzing not only project-specific data, but also by combining data across multiple domains of inquiry inherent in the different component projects.